1. Field of the Invention
The present invention relates to a medical device for administering a drug to a patient. More specifically, the present invention relates to a micro infusion drug delivery device.
2. Description of the Related Art
Infusion pumps are used to deliver various types of solutions subcutaneously to patients. There are many medical conditions that require the administration of liquid medicaments transcutaneously (through the skin) for prolonged periods. Diabetes, for example, may be controlled by daily, or more frequent, injections of insulin. The ability to administer numerous small dosages of insulin has been proven to be the best way to insure tight glucose control for a patient. The National Institute of Health (NIH) conducted a long-term study of people with diabetes known as the Diabetes Complications and Control Trial (DCCT) were it was determined that the proper management of diabetes requires 4 or more injections of insulin per day. However, current devices either are not convenient or easy to use by patients. Syringes and insulin pens all require the patients to inject themselves and do not provide a convenient or discreet mechanism to accomplish medication delivery.
Since transcutaneous injections are painful and troublesome, and since each injection represents a possibility for infection, injections are spaced at intervals as far apart as possible, resulting in peak and valley concentrations of the medicament in the bloodstream or at the site in the body requiring the medicament, the peak concentrations occurring shortly after the administration of the medicament and the low, or valley, concentrations occurring shortly before the administration of the next injection. This method of administration exposes the patient to the possibility of overdose at peak levels and underdose at valley levels, but was nevertheless the standard method for many years in the absence of a better alternative.
Recently, systems have been developed in which a catheter is semi-permanently implanted in a patient to provide access to a transcutaneous site in a patient""s body, and a liquid medicament is supplied to the catheter from a reservoir. However, many patients find that the infusion site forms small red marks that are the result of irritation from the infusion at a single point. Infusing the medication either by bolus injection or reducing the amount of medication infused at any one specific site relieves this irritation.
U.S. Pat. No. 3,964,484 by Gerstel, et al. describes a drug delivery device for percutaneously administering a drug comprising a plurality of projections, a drug reservoir containing a drug, and where the projections extend from the reservoir and are adapted for penetrating the stratum corneum for percutaneously administering a drug from the reservoir to produce a local or systemic physiological or pharmacological effect.
U.S. Pat. No 4,235,234 discloses a subcutaneous injection system for injecting fluids in the subcutaneous fat layer of a patient including an injection needle having a sharpened end thereon for penetrating the subcutaneous fat layer of the patient and a locator pad carrying the needle with the locator pad having a locating surface to lie against the patient""s skin from which the sharpened end of the needle projects a prescribed distance while oriented generally normal to the locating surface to positively control the depth of penetration of the sharpened end of the injection needle into the subcutaneous fat layer of the patient.
U.S. Pat. No. 4,969,871 discloses a drug formulation chamber for an intravenous administration set is provided. The intravenous administration set includes a container of an IV fluid, a drip chamber, a drug formulation chamber, and an adapter-needle assembly. The drug formulation chamber has a fluid inlet and a fluid outlet for maintaining a flow of IV fluid through the chamber. A portion of the chamber wall is comprised of a window material which allows the drug to diffuse therethrough but which prevents convective loss of the IV fluid. A flow distributor is provided within the chamber for distributing the flow of IV fluid along the interior surface of the window. A transdermal-type drug delivery device is adhered to the exterior surface of the window. Drug is delivered by the delivery device through the window and into the flowing IV fluid. The device delivers drug into the IV fluid at a rate that is independent of the flow rate of IV fluid through the formulation chamber. The rate of drug delivery from the device into the IV fluid is controlled by either the window itself or by a membrane layer in the drug delivery device. A plurality of drug delivery devices may be adhered to the window to deliver a plurality of drugs or to deliver a single drug at a higher dosage rate. A similar window may be placed in an IV bag to deliver a drug into the IV fluid therein.
U.S. Pat. No. 6,083,196 discloses a device comprising a sheet member having a plurality of microprotrusions for penetrating the skin and a substantially incompressible agent reservoir housing contacting and extending across the sheet member for transmitting a hold-down force applied the sheet member to maintain the microprotrusions in skin-piercing relation to the skin, even during and after normal patient body movement.
U.S. Pat. No. 6,050,988 discloses a device comprising a sheet member having a plurality of microprotrusions extending from a bottom edge for penetrating the skin of a patient. The sheet member when in use being oriented in an approximately perpendicular relation to the patient""s skin.
U.S. Pat. No. 5,587,326 discloses a method and apparatus for mechanically disrupting a layer of skin having a known thickness without substantially disrupting underlying dermis layers below the layer of skin in question so as to facilitate the delivery of compounds across the disrupted layer. The apparatus includes a cutter having a plurality of microprotrusions having a height chosen with respect to the layer of skin that is to be disrupted and a stop for preventing the apparatus from penetrating the skin beyond a predetermined distance.
U.S. Pat. No. 6,022,316 discloses an apparatus and a method for electroporating tissue. At least one micropore is formed to a predetermined depth through a surface of the tissue, and electrical voltage is applied between an electrode electrically coupled to the micropore and another electrode spaced therefrom. By applying electroporation to tissue that has been breached by a micropore, the electroporation effects can be targeted at tissue structures beneath the surface, such as capillaries, to greatly enhance the withdrawal of biological fluid, and the delivery for uptake of compounds into the tissue.
It is a general object of the invention to provide a new and improved infusion pump which is adapted for use with pre-filled single dose containers and configured for use with a catheter or skin interface device configured from a plurality of micro projections either attached directly to the pump or by means of a catheter.
Another object of the invention is to provide a catheter which utilizes a skin interface device that breaches the stratum corneum with multiple lumin projections and is connected to a micro infusion device that is capable of providing a relatively constant infusion of medication or bolus injections on demand. This gives the patient a more comfortable infusion and minimizes the irritation from the infusion process.
Another object of the invention is the formation of the micro projection lumens from micro-machined components using semi conductor processes.
Another object is to provide an infusion pump of the type described which eliminates the need for the patients to separately transfer the medications into containers used with the pump, and thereby minimize costly preparation steps.
Another object is provide an infusion pump of the type described which accurately dispenses the medication at a controlled pressure and for a controlled period of time which enables the use of a micro projection skin interface device.
Another object is to provide an infusion pump of the type described which includes a control system with safety features.
Another object is to provide an infusion pump of the type described which achieves health benefits by obviating the risk of contaminating the medication by transferring the medication from primary container to one which is compatible with the pump and providing an alarm in the case where the solution is not completely delivered to the patient.
Another object is to provide an infusion pump which is small in size to permit discrete infusion of medication.
Another object is to provide an infusion pump of the type described which accurately dispenses medication at a controlled pressure and for a controlled period of time.
Another object is to provide an infusion pump of the type described which includes a control system with is capable of supporting both basal rate delivery and bolus delivery.
Another object is to provide an infusion pump of the type described which achieves health benefits by obviating the risk of contaminating medication solution by using prefilled cartridges